C
Explanation:
that's just what I learned in school
The force needed to accelerate an elevator upward at a rate of
is 2000 N or 2 kN.
<u>Explanation:
</u>
As per Newton's second law of motion, an object's acceleration is directly proportional to the external unbalanced force acting on it and inversely proportional to the mass of the object.
As the object given here is an elevator with mass 1000 kg and the acceleration is given as
, the force needed to accelerate it can be obtained by taking the product of mass and acceleration.


So 2000 N or 2 kN amount of force is needed to accelerate the elevator upward at a rate of
.
There's a very subtle thing going on here, one that could blow your mind.
Wherever we look in the universe, no matter what direction we look,
we see the light from distant galaxies arriving at our telescopes with
longer wavelengths than the light SHOULD have.
The only way we know of right now that can cause light waves to get
longer after they leave the source is motion of the source away from
the observer. The lengthening of the waves on account of that motion
is called the Doppler effect. (The answer to the question is choice-c.)
But that may not be the only way that light waves can get stretched. It's
the only way we know of so far, and so we say that the distant galaxies
are all moving away from us.
From that, we say the whole universe is expanding, and that right there is
one of the strongest observations that we explain with the Big Bang theory
of creation.
Now: If ... say tomorrow ... a competent Physicist discovers another way
for light waves to get stretched after they leave the source, then the whole
"expanding universe" idea is out the window, and probably the Big Bang
theory along with it !
Now that our mind has been blown, come back down to Earth with me,
and I'll give you something else to think about:
It's true that when we look at distant galaxies, we do see their light
arriving in our telescopes with longer wavelengths than it should have.
And then we use the Doppler effect to calculate how fast that galaxy
is moving away from us. That's all true. Astronomers are doing it
every day. I mean every night.
So here's the question for you to think about ... maybe even READ about:
When the light from a distant galaxy pours into our telescope, and we
look at it, and we measure its wavelength, and we find that the wavelength
is longer than it should be ... how do we know what it should be ? ? ?
Answer: True
A water pump
belong to a positive displacement pump that provides constant flow of water at
fixed speed, regardless of changes in the counter pressure. The two main types
of positive displacement pump are rotary pumps and reciprocating pumps.
Moreover, water
pump is a reciprocating positive displacement pump that have an expanding
cavity on the suction side and a decreasing cavity on the discharge side. In
water pumps, the liquid flows into the pumps as the cavity on the suction side
expands and then the liquid flows out of the discharge as the cavity collapses
providing water in a pail.
a. 0.5 T
- The amplitude A of a simple harmonic motion is the maximum displacement of the system with respect to the equilibrium position
- The period T is the time the system takes to complete one oscillation
During a full time period T, the mass on the spring oscillates back and forth, returning to its original position. This means that the total distance covered by the mass during a period T is 4 times the amplitude (4A), because the amplitude is just half the distance between the maximum and the minimum position, and during a time period the mass goes from the maximum to the minimum, and then back to the maximum.
So, the time t that the mass takes to move through a distance of 2 A can be found by using the proportion

and solving for t we find

b. 1.25T
Now we want to know the time t that the mass takes to move through a total distance of 5 A. SInce we know that
- the mass takes a time of 1 T to cover a distance of 4A
we can set the following proportion:

And by solving for t, we find
